Joanne thanks so much for that - it's really helpful. And you're absolutely right on both counts. I can't do much about the light colours on the edges - these blocks only can be made one way unlike the hexes that you can turn 3 ways. But I CAN and will pay more attention to the setting corners next time. :-D
Edited to say - perhaps on the layout, if the light edge ones butt up to each other, that will help too.